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요소 연결 매개법을 이용한 선형 구조물의 동적 컴플라이언스 최적화
윤길호,Yoon, Gil-Ho 한국전산구조공학회 2009 한국전산구조공학회논문집 Vol.22 No.3
본 연구 논문에서는 요소 연결 매개법(Element Connectivity Parameterization Method)을 이용하여 선형 구조물의 동적 컴플라이언스(Dynamic compliance)를 최소화하는 위상을 설계하는 기법을 연구한다. 기존의 밀도를 기반으로 한 위상최적화기법은 각 유한 요소의 탄성계수를 각 요소에 정의되어 있는 설계변수(Design Variable)를 이용하여 위상최적화를 수행한다. 이 방법은 현재까지 많은 선형구조문제에 적용되었지만 비선형 문제와 멀티피직스 시스템에서 수치적인 문제점이 보고되었다. 이런 문제점을 근본적으로 해결하기 위하여 최근에 요소 연결 매개법(Element Connectivity Parameterization Method)이란 새로운 최적화 기법이 개발되었다. 이 새로운 설계 방법은 요소의 강성을 설계하는 것이 아니라 요소의 연결성을 설계하는 기법으로 이를 이용하여 비선형 구조물이나 멀티피직스 시스템의 위상최적화를 효과적으로 수행할 수 있다. 하지만, 아직까지 질량 행렬의 정의에 대한 모호함으로 인하여 동적인 구조물의 최적화에 대한 연구가 많이 이루어지지 않았다. 이런 문제점을 해결하기 위하여 요소 연결 매개법에서 질량행렬을 정의하는 방법을 연구하며, 이를 이용하여 선형 구조물의 동적 컴플라이언스(Dynamic Compliance)를 고려한 위상최적화 문제에 적용하여 제안된 방법을 검증하였다. This paper studies the Element Connectivity Parameterization Method(ECP method) for topology optimization considering dynamic compliance. The previous element density based topology optimization method interpolates Young's modulus with respect to design variables defined in each element for topology optimization. Despite its various applications, these element density based methods suffer from numerical instabilities for nonlinear structure and multiphysics systems. To resolve these instabilities, recently a new numerical method called the Element Connectivity Parameterization(ECP) Method was proposed. Unlike the existing design methods, the ECP method optimizes the connectivities among plane or solid elements and it shows some advantages in topology optimization for both nonlinear structure and multiphysics systems. In this study, the method was expanded for topology optimization for the dynamic compliance by developing a way to model the mass matrix in the framework of the ECP method.
윤길호(Gil Ho Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
This paper presents a new monolithic approach for topology optimization for stationary fluid-structure interaction problem. It is common to analyze coupled fluid-structure interaction structures by solving stationary Navier-Stokes equation and linear elasticity equation separately. Although they are plenty of researches improving structural responses by changing size or/and shape of structures using a staggered analysis method, it is still difficult to conduct topological optimization for fluid-structure interaction problems. To resolve issues in topology optimization, this paper introduces a new monolithic approach assuming stationary fluid. To reflect structural deformation on stationary Navier-Stokes equation in Eulerian domain, the fluid equation and the differential operator after structural deformation are transformed using the deformation tensor calculated by structural displacements. Using the present approach, we can optimize fluid¬structure interaction structures.
요소 연결 매개법의 응용 : 비선형 복합 물리계의 위상최적화
윤길호(Yoon Gil Ho),김윤영(Kim Yoon Young) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.10
Although topology optimization has been applied in many engineering problems, the classical element density based approach has some theoretical problems such as nonlinear material interpolation with respect to the design variable, the unphysical solution in heat transfer problems, and the unstable elements problem for geometrical nonlinear structures. In order to resolve these difficulties, the newly proposed element connectivity parameterization method or ECP method is adopted as an alternative methodology for topology optimization in this paper. To show the validity of the proposed approach, the topological design of nonlinear structures and an electro-thermal-compliant actuator was considered.
가진 주파수에 종속적인 음향 시스템을 위한 Multifrequency quasi-static Ritz vector method의 개발
윤길호(Gil Ho Yoon) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This study extends the well-established Ritz vector (RV) and quasi-static Ritz vector (QSRV) method for acoustic problem which are frequency dependent. Unlike the standard RV or QSRV methods, the direct Krylov subspace bases without the orthogonalization process calculated for multiple center frequencies are used. Through several analysis examples, we can confirm that from an engineering point of view, this direct usage of the Krylov subspace bases is effective in calculating the responses of acoustic system. Through several analysis examples, the efficiency and reliability of the developed model reduction schemes for acoustic problems are compared and validated.
윤길호(Gil Ho Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
This paper develops a new for topology optimization scheme for heat dissipating structure considering forced convection. To cool down small electric devices, natural and forced convection models have been used. Recently, many engineering application areas such as electrochemical conversion device or fuel cell device adopt the forced convection to transfer generated heat. Therefore, it becomes important to design shapes of flow channels. This paper studies optimal topological designs considering fluid heat interaction. The incompressible Navier stokes equation and the Poisson's equation are sequentially solved. This paper presents optimal channel design considering forced convection.